Case Studies
4
The case studies in this chapter illustrate techniques and methods that are discussed in
this Guide. They are presented in order of climate zone, from warmest to coldest. Energy
numbers are provided to benchmark these buildings against future buildings; however, all
these case studies predate the publication of the Guide, and they were not developed using the
recommendations in Chapter 3. These schools may or may not have achieved the 30% level
if they had been constructed entirely according to the recommendations in this Guide. You
are encouraged to view additional case studies and submit your own at www.ashrae.org/aedg.
Case studies provide motivation and examples for others to follow.
Zone 1—Waipahu Intermediate School
Waipahu, Hawaii
The Hawaii Department of Education piloted the Waipahu Intermediate School
(WIS) cafeteria as a LEED project in educational facilities to support its commitment
to conserve resources and provide better facilities. The 19,200 ft2 cafeteria, opened for
the 2006–2007 school year, is designed to serve 750 people at a time.
Daylighting features include shaded north- and south-facing clerestories and jalousies designed to bounce indirect daylight deep into the dining area. This reduces the
electric lighting requirements by more than 55%. The roof was designed to create a
thermal chimney for stack-effect ventilation, which, in addition to cross-ventilation,
eliminates the need for ceiling fans and ductwork.
The State of Hawaii Department of Business, Economic Development, and Tourism Report, Analyses of Economic, Environmental and Occupant Benefits of Sustainable Design, and LEED Certification for State of Hawaii and Public School Facilities,
included the development of two energy-use scenarios for the cafeteria example: a base
case (built to code) and a green case (incorporating high-performance features). The
green case resulted in a 16% energy reduction. The kitchen area in the cafeteria example was primarily designed with conventional methods, so its energy use is assumed
to be the same for both cases.
58 | Advanced Energy Design Guide for K-12 School Buildings
Figure 4.1. Cafeteria building exterior views.
© 2007 David Franzen
Figure 4.2. Cafeteria interior view.
Table 4.1. Waipahu Intermediate School Cafeteria
Energy Saving Measures
Description of Elements
Tips
Envelope
Building Orientation
Long east-west axis
DL9
T-8s
EL2
Lighting
Lighting Systems Used
Daylighting
Window Design
Clerestories with overhangs
DL1–10
HVAC
Natural cooling and ventilation
EN22, HV32
SWH
High-efficiency boiler
WH1–6
Fully commissioned
HV23, CX1–13
High-efficiency gas equipment
AS2
System Controls
Commissioning
Additional Savings
Kitchen Equipment
Energy-Use Characteristics
Baseline Electric Energy Use
14.0 kBtu/ft2⋅yr
Simulated Electric Energy Use
11.7 kBtu/ft2⋅yr
Photos and data are provided by the Hawaii Department of Business, Economic Development, and Tourism.
Chapter 4—Case Studies | 59 Zone 2—Desert Edge High School
Goodyear, Arizona
Desert Edge High School, west of downtown Phoenix, was constructed in two
phases for a total of 218,783 ft2 and a student capacity of 1600. Phase II was certified
LEED Silver in 2006. The total build cost of the school was $21.3 million at an average
of $97/ft2. Phase one was opened in time for the 2002–2003 school year, and phase two
opened in time for the 2005–2006 school year. This climate zone 2 facility includes
classrooms, administrative areas, a media center, a gymnasium, a 522-seat fine arts
auditorium, a career technology area, and a student bookstore in the core. An in-school
kiosk showcases many of the unique features of the high school through a virtual tour
and the display of electricity, water, and carbon dioxide (CO2) savings. The kiosk also
displays real-time animations of the heating and cooling systems, an interactive building directory, bus routes and schedules, real-time weather conditions, and more.
Desert Edge is about 28% more energy efficient than other comparable high schools.
The energy efficiency equates to roughly $58,000 in cost savings per year. The school
showcases high-performance building strategies and features for a hot/dry climate zone,
including an improved building envelope, daylighting, demand-controlled ventilation,
and high-efficiency water-cooled chillers with a water-side economizer. The masonry
walls include R-19 cavity insulation, and R-30 insulation is used on the built-up metal
deck roof. The windows are high performance, low-e dual-paned glass windows with
a U-factor of 0.33. The lighting system takes advantage of daylighting and uses a lowlighting power density to reduce the amount of artificial lighting. Lighting power density is 1.09 W/ft2 in classrooms and 1.04 W/ft2 in the gymnasium. Daylighting controls
and occupancy sensors further reduce lighting loads. Multiple light switches are used
to allow the teachers and students to light only the occupied space when daylighting is
not sufficient. A high-efficiency central cooling and heating system uses two centrifugal
chillers with a water-side economizer cycle and plate-and-frame heat exchanger. The
water-based cooling towers include a chiller bypass to take advantage of indirect evaporative cooling possible in the dry climate. Classrooms have CO2 sensors that control outdoor air for the fan-coil units.
Figure 4.3. Building exterior with window shading.
60 | Advanced Energy Design Guide for K-12 School Buildings
Figure 4.4. Building exterior.
(a)
(b)
Figure 4.5. (a) Centrifugal chiller and (b) cooling tower.
Table 4.2. Desert Edge High School
Energy Saving Measures
Description of Elements
Tips
Envelope
Building Orientation
Long east-west axis
DL9
Opaque Components
Concrete block with R-19 insulation and R-30 built-up roof
EN5
Vertical Glazing
Low-e glass with a grey tint; assembled U-factor of 0.33
EN19–20
Lighting
Lighting Systems Used
T-8 lighting in most of the school with a lighting power density of 1.09 W/ft2
EL1–2, EL9–12
in classrooms, 1.04 W/ft2 in the gym, and 1.27 W/ft2 in the auditorium
Controls
Dual technology occupant sensors used in offices, administrative, and
support areas; wall switch occupancy sensors are installed in small
offices, storage, or other similar areas
EL6, EL8
Window Design
Low-e with double glazing and a third pane for integral microblinds
DL1–4, DL9–12
Controls
Daylight sensors used in conjunction with motion sensors
DL13, DL17–18
HVAC central cooling and heating use high-efficiency centrifugal
chillers with a hydronic economizer cycle with plate and
frame heat exchanger and variable-speed pumps
HV10
Daylighting
HVAC
Equipment
System Controls
Measurement and Verification
DDC system with Web-based metering and feedback
Temperature Control
Individual room controls
CO2 Sensors
Installed in each zone of the building to for demand controlled ventilation
Energy-Use Characteristics
28% better than ASHRAE Standard 90.1-1999
Photos and data are provided by Emc2 Group Architects Planners, Inc.
Chapter 4—Case Studies | 61 Zone 3—Homewood Middle School
Homewood, Alabama
Homewood Middle School in climate zone 3 is a 190,000 ft2 facility with a capacity
of 1000 students. The school consists of a classroom wing, an administration wing, and an
activity wing. The cost to build the school was $23 million, or $121/ft2. Homewood opened
in January 2005, replacing an old school on the same site that was originally built in 1955.
When the time came to design the new building, the designers and school district worked
together to create an energy-efficient, sustainable building. The result is a school that is
36% more energy efficient than ASHRAE Standard 90.1-1999.
Daylighting is is used throughout the building as one of the primary strategies to
achieve energy-efficiency goals. Ninety-five percent of the school utilizes daylighting,
and all classrooms in the school have exterior windows. Shading devices, such as overhangs, are used on the south side of the school to reduce solar heat gain and glare in the
school. Light shelves are used to project light deeper into the school. Windows on the
north side of the school are large to increase the amount of indirect daylight in the school.
Electrical lighting is controlled by photo sensors and occupancy sensors to make use of
available daylighting and reduce electricity usage. Additional strategies include the following:
•
•
•
Mass walls are insulated with R-10 continuous insulation
CO2 sensors in the gym control the local HVAC system
A 9.8 EER central chiller VAV HVAC system utilizes air-side economizers
Figure 4.6. Homewood Middle School.
62 | Advanced Energy Design Guide for K-12 School Buildings
Figure 4.7. Building exterior with light shelves.
(a)
(b)
Figure 4.8. (a) Large north-side windows and (b) school corridor.
Table 4.3. Homewood Middle School
Energy Saving Measures
Description of Elements
Tips
Envelope
Building Orientation
Long east-west axis
DL9
Opaque Components
Mass walls R-10 c.i.
EN5
Occupancy sensors and photocell dimmable control
EL6, EL8
Daylighting in all classrooms, gym
DL1–4
Equipment
9.8 EER chiller, VAV
HV5
Cooling Tower
Air cooled
Lighting
Controls
Daylighting
Window Design
HVAC
System Controls
Measurement and Verification
Yes
Energy Use Characteristics
36% savings over ASHRAE Standard 90.1-1999
Measured Energy Cost
1.24 $/ft2⋅yr
Measured Energy Use
64.4 kBtu/ft2⋅yr
Years of Measured Data
2 years
HV23
Chapter 4—Case Studies | 63 Zone 4—Knightdale High School
Knightdale, North Carolina
Knightdale High School in climate zone 4 is part of the Wake County School District.
The 281,000 ft2 building was completed for the 2004–2005 school year at a project cost
of $26.5 million, or about $95/ft2. The school was built for 1600 students and includes
classrooms, offices, public assembly areas, a cafeteria, a gymnasium, athletic fields, and
restrooms. The Triangle “J” High Performance Guidelines Version 1.0 guided the design
and construction of this building.
The building team committed to high-performance design from the beginning.
The project was designed to use 58.7 kBtu/ft2, and after three years it is operating at
54.4 kBtu/ft2, annually.
Clerestories provide daylighting in the main entry, the dining commons, and the
media center. Additional daylighting is provided by skylights in the dining area and gym
corridor. The classrooms in the three-story wing feature large windows to provide daylighting, exterior shading devices on the south-facing windows to control direct sunlight
and reduce solar heat gain, dimmable and independently controlled lighting to control
daylighting, and multiswitching modes for general classroom lighting.
The building is heated and cooled with a four-pipe chilled- and hot-water system.
Hot water is supplied by five high-efficiency condensing boilers, and the chilled water
is supplied by standard-efficiency air-cooled chillers. Conditioned air is provided to the
classrooms and administration areas with VAV AHUs through a VAV terminal box and
hot-water reheat coil in each space. Relative humidity is monitored in the AHU return duct
and controlled via AHU fan speed, cooling coils, and heating coils. The HVAC system is
controlled through a DDC system.
Figure 4.9. Knightdale High School.
64 | Advanced Energy Design Guide for K-12 School Buildings
(b)
(a)
Figure 4.10. (a) Clerestory at main entrance and (b) classroom lighting system.
Table 4.4. Knightdale High School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
North-south
DL9
Opaque Components
Roof/ceiling R-26; walls R-16
EN3, EN7
Vertical Glazing
Door/window assemblies U = 0.81
EN13
Dimmable controls in classroom; separate general purpose
lighting controls
EL2, EL8
Large windows in three-story section
DL1–DL4
Exterior light shading on south-facing windows
DL12, DL20, DL22
Lighting
Controls
Daylighting
Window Design
Clerestories and skylights in common areas
HVAC
Equipment
Standard chiller with variable-frequency drive pumps
HV25
Boilers
Condensing boilers
HV26
Natural Ventilation
VAV system with humidity-controlled cooling and reheat coils;
air-handling units (AHUs) use variable-frequency drives and are
outfitted with OA economizers for cooling with OA when possible
HV5–6
SWH
Natural gas-fired atmospheric water heater with storage tank,
mixing valves and hot water recirculation pumps. SWH system is
WH1–2
connected to a digital direct control system or scheduling of operation.
System Controls
Ventilation
Direct digital control system; OA and CO2 intake is monitored for each
AHU
HV23
Additional Savings
Exterior/Field/Parking Lot Lighting
The sports field lighting fixtures are provided with internal louvers and
hood visors to reduce glare and light trespass off of school property.
EX1–2
Energy Use Characteristics
Simulated Energy Use
58.7 kBtu/ft2⋅yr
Measured Energy Use
54.4 kBtu/ft2⋅yr
Years of Measured Data
3 years
Photos and data are provided by the Boney Architects and Wake County Public Schools System.
Chapter 4—Case Studies | 65 Zone 4—Third Creek Elementary School
Statesville, North Carolina
Third Creek Elementary School in Statesville is located in a suburban setting in climate zone 4. The 92,000 ft2 building was completed in July 2002 at a total project cost
of $8.7 million, or $95/ft2 (land purchase excluded). This new construction project consolidated and replaced two aging schools. The finished school was the first K-12 school
to earn a LEED v2.0 Gold Certification from the USGBC. Spaces include classrooms,
offices, public assembly spaces, cafeteria, gymnasium, athletic field, and restrooms.
The building team made a commitment to high-performance design from the beginning of the project. Examples are the gymnasium, stage, and dining room, which
are located so they operate on separate systems for after-hours community use while
the academic portion of the school is secured and not using energy. Energy demand
was lowered though energy-efficient equipment and design, including extensive daylighting. Third Creek has an east-west axis orientation, with most classrooms facing
either north or south. The southern façade has overhangs on the windows to shade
from the summer sun. Each of the classrooms makes use of lightshelves to promote
the dispersion of daylight. In addition to the lightshelves, reflective ceiling tiles
were used to increase the effectiveness of daylighting. Also, in addition to the lighting systems employed within the school, Third Creek makes use of efficient exterior
lighting.
Energy modeling shows a reduction in annual energy costs of 25% over ASHRAE
Standard 90.1-1999. After the first year of operation, energy reduction increased each year
to a 33% reduction in 2005.
Figure 4.11. Floorplan showing north- and south-facing classroom wings.
66 | Advanced Energy Design Guide for K-12 School Buildings
© 2007 Sparks Productions.
(a)
(b)
Figure 4.12. (a) Full exterior with view of main entrance and (b) classroom with internal light shelves.
Table 4.5. Third Creek Elementary School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
Long east-west axis, classrooms facing north and south
DL9
Opaque Components
R-45 roof, R-22 walls
EN3, EN7
Vertical Glazing
Aluminum windows low-e; view glass 46% transmittance center
of glass; light shelves glass; 70% transmittance center of glass
EN24
Lighting
Classroom T8
EL2
Controls
Four levels of control per classroom
EL8
Occupancy sensors
EL6, DL13, L16–18
Overhangs on southern façade
DL20
Interior light shelves in all classrooms
DL22
Equipment
High-efficiency water-source heat pumps w/ variable-frequency
drives—14.5 EER; COP of 4.5
HV2
Boilers
97% thermal efficiency—condensing
HV26
Cooling Tower
5 levels of control to match loads with minimal energy output
Energy Recovery Ventilators
Control humidity not to exceed 55%
HV8–9
Measurement and Verification
Direct digital control system
HV23
Temperature Control
Classroom by classroom basis
Daylighting
Window Design
HVAC
System Controls
Additional Savings
Computers
ENERGY STAR
AS2
Energy Use Characteristics
Simulated Energy Use
59.6 kBtu/ft2⋅yr
Measured Energy Use
59.8 kBtu/ft2⋅yr (purchased)
Years of Measured Data
3 years
Photos are provided by Spark Productions and data is provided by Moseley Architects.
Chapter 4—Case Studies | 67 Zone 5—Bolingbrook High School
Bolingbrook, Illinois
Bolingbrook High School in Bolingbrook, Illinois, is located in a suburban setting in
climate zone 5. The 569,000 ft2 building has a rated capacity of 3600. A master plan for the
district included the new high school and renovations to two other high schools, one of which
became a middle school. The total project cost for the new school was $96 million, or about
$169/ft2. With a commitment to high-performance design, the building team registered the
project with the USGBC.
The educational planning concept of school-within-a-school was used in the design,
with two academic houses in distinct wings and interior courtyards to maximize exterior
views and daylight. In addition, the school incorporated a theatrical performance auditorium,
a physical education gym, and a field house that is partially buried to reduce scale. Energy
and environmental features include use or inclusion of the following:
•
•
•
•
•
•
•
A fully automated digital control system that allows for automatic control of HVAC
systems turning on/off via a time schedule set according to the projected use of the
different areas
Fans that do not run unless scheduled and room thermostats that are digitally programmed
between 68°F and 74°F so as to optimize energy savings
Lights equipped with override switches that automatically turn on via a programmed
schedule before school starts and automatically turn off after school
Lights that are equipped with daylight harvesting sensors in the upper levels of the
main concourse
A condensate recovery system projected to save 360,000 gallons of water annually that
collects and reuses water from the rooftop chillers
Bio-swales to filter impurities from surface-water runoff
A well-irrigation system for athletic fields and indigenous plantings
Figure 4.13. Bolingbrook High School interior courtyard.
68 | Advanced Energy Design Guide for K-12 School Buildings
(a)
(b)
(c)
Figure 4.14. Daylighting and lighting views of (a) main corridor, (b) media center, and (c) cafeteria.
Table 4.6. Bolingbrook High School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
Classrooms facing courtyards
Opaque Components
2 in. rigid wall insulation in cavity with core insulation in CMU
Vertical Glazing
1 in. insulated low-e glass
EN19
Roofing System
PVC membrane with white reflectance
EN1
Lighting
T-8 lamps in classrooms, metal halide in hallways
EL2, EL5
Controls
Automatic turnoff based on schedule with override
capability in one-hour increments
Hallways: light sensors to auto turn off when
daylight is sufficient;
Classrooms: two switches to allow for 33%, 67% and
100% lighting
EL1–2, EL5, EL8,
DL16–17
90% of occupied spaces have daylighting;
controls on main corridor with clerestory
DL1–4, DL16–17
Constant primary pumping and secondary VSD pumping
HV5–6
Cx
Full Cx included
HV23
Temperature Control
Individual classrooms
Daylighting
Window Design
HVAC
Pumps
System Controls
Additional Savings
Exterior/Field/Parking Lot Lighting
Metal halide cut-off with 0 ft candles at lot line
EX1–2
Energy Use Characteristics
Simulated Energy Use
86.6 kBtu/ft2⋅yr (from LEED submittal)
Measured Energy Use
91.4 kBtu/ft2⋅yr
Years of Measured Data
3 years (school operates 13 or more hours per day,
7 days per week)
Photos and data are provided by Wight & Company.
Chapter 4—Case Studies | 69 Zone 5—Whitman-Hanson Regional High School
Whitman, Massachusetts
Whitman-Hanson Regional High School in climate zone 5 is a 234,500 ft2 building
designed for 1350 students. The total construction cost was $41 million, or $175/ft2. The
school is a pilot project for the Massachusetts Green Schools Initiative, a partnership between the Massachusetts School Building Authority and the Massachusetts Technology
Collaborative (MTC).
Whitman-Hanson is 39% more efficient than ASHRAE Standard 90.1-1999. It
makes use of daylighting, a well-insulated envelope, energy-efficient mechanical systems, a white roof, and energy-efficient appliances to reduce energy use. Natural light
is used in the library, a two-story lecture hall, the classrooms, a performing arts center,
and a double gymnasium to reduce the electrical lighting. The cafeteria is lit with natural light through skylights and daylight harvesting. Daylighting sensors are used in each
classroom and the gymnasium to control electrical lighting, which comes from high-efficiency fluorescent fixtures, including pendant-mounted, direct/indirect lighting fixtures.
The average lighting power density in the school is 1.15 W/ft2. The exterior walls are
insulated with R-10 continuous insulation and 6 in. wall-cavity insulation. Under-slab
insulation is used on the floors. The windows are highly insulated and low-e coated to
reduce heat loss. They are designed to allow natural light to penetrate further into the
building spaces.
The HVAC system helps reduce energy use. Occupancy sensors are used throughout the building to provide adequate heating and cooling. Based on the occupancy,
heating and air conditioning of each classroom is controlled by ventilation dampers
and VAV boxes. A high-efficiency hybrid chiller is used. The primary base load chiller
is a high-efficiency water-cooled chiller, and an air-cooled chiller provides additional capacity for peak periods. High-efficiency condensing boilers, demand-controlled
ventilation with an energy recovery system, and variable-flow pumping are additional
HVAC energy saving features.
A 51-kW PV system on the roof supplies approximately 5% of the annual energy that
is consumed and has become part of the students’ curriculum. The school uses the money
it saves on energy to purchase high-tech (state of the art) educational aids, including interactive whiteboards and LCD projectors for all classrooms. Other teaching aids include a
distance-learning center, cyber cafes, and instructional kiosks.
Figure 4.15. Whitman-Hanson regional high school exterior.
70 | Advanced Energy Design Guide for K-12 School Buildings
(b)
(a)
Figure 4.16. (a) Daylighted library and (b) classroom.
Table 4.7. Whitman-Hanson Regional High School
Energy Saving Measures
Description of Elements
Tips
Envelope
Building Orientation
Long east-west axis
DL9
Opaque Components—Exterior Walls
R-10 c.i. plus 6 in. wall cavity insulation
EN7
Opaque Components—Floors
Under slab insulation
EN10
Vertical Glazing
Low-e
EN19
Lighting
Lighting System
High-efficiency fluorescent fixtures including pendant-mounted direct-indirect
lighting fixtures
2
EL1–2
LPD
1.15 W/ft average in the school
EL9
Controls
Photosensors in each classroom and the gymnasium
DL17
Daylighting
Window Design
Highly insulated and low-e coated
Natural Light
Used in the library, two-story lecture hall, classrooms, performing arts center, and double
DL36
gymnasium to reduce the use of electrical lighting
Skylights
Used in the cafeteria with daylight harvesting
DL28
Equipment
Water-cooled chiller for base load; air-based chiller used only for peaking
HV25
Boilers
High-efficiency condensing boiler
HV26
Occupancy sensors control ventilation dampers and VAV boxes to adjust the heating
and A/C in each classroom.
HV5–6
51 kW PV system on the roof
AS6
HVAC
System Controls
Temperature Control
Additional Savings
Renewable Energy
Green Technology Cost Information
Total Capital Cost
2.83% of the total cost
Incremental Cost
$4.85/ft2
Incentives Received
$475,000 of the total $580,000 PV system from MTC
Expected Payback (w/o Incentives)
Nine years (excluding the solar electric generation)
Expected Payback (w/Incentives)
Almost immediate (incentives paid most of the initial cost for the green technology)
Energy Use Characteristics
39% better than ASHRAE Standard 90.1-1999
Measured Energy Use
60.5 kBtu/ft2⋅yr (utility bills)
MeasuredEnergy Cost
1.80 $/ft2⋅yr
Years of Measured Data
3 years
Chapter 4—Case Studies | 71 Zone 6—Westwood Elementary School
Zimmerman, Minnesota
Westwood Elementary School is located in a mixed suburban/rural setting in climate
zone 6. The 75,000 ft2, two-story building has a current capacity of 500 students, and the
core facilities have a capacity of 750 students. The school opened in the fall of 2004 and
was built at a cost of $12 million, or $160/ft2. Spaces include classrooms, offices, public
assembly areas, cafeteria, gymnasium, and athletic field. The school used LEED as the
design guidance and was the first K-12 school in Minnesota and the fourth in the nation to
earn LEED v2.1 certification.
The building was oriented on the site to maximize solar and wind patterns. The highperformance design included increased insulation, daylighting, energy-efficient lighting
with occupancy sensors, low-e glass to control heat gain and loss, displacement ventilation, energy-efficient gas kitchen equipment, and a condensing boiler for heating needs.
Operable windows add to the energy-saving features and allow for passive ventilation.
The building was designed to meet multiple community and school needs. The gymnasium, stage, and dining room are located strategically so they operate on separate systems after hours.
In order to cut energy use and peak loads, Westwood uses energy recovery ventilators (ERVs). ERVs can recover as much as 80% of the energy from the exhaust
airstream and transfer it to the supply airstream for heating and humidification in
the winter months. The use of ERVs in the winter can cut humidification costs by
up to 60%. The ERVs are used in the opposite manner for cooling in the summer
months and transfer sensible and latent energy from the ventilation air to the exhaust airstream.
The original design projected an energy use of 53.7 kBtu/ft 2 annually; however, the actual building operation has been modified from what was modeled due
to year-round cooling. During the first three years of operation, the actual annual
energy used to operate this building has been 75.9–84.0 kBtu/ft 2, with an average
of 78.4 kBtu/ft 2.
Figure 4.17. Westwood Elementary School aerial photo.
72 | Advanced Energy Design Guide for K-12 School Buildings
Figure 4.18. Pulse condensing boiler.
Table 4.8. Westwood Elementary School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
Long east-west orientation for classrooms
DL9
Opaque Components
Roof insulation: R-22
Wall insulation: R-18
EN3, EN7
Roofing
5-ply built up roof
Vertical Glazing
U-factor: 0.29
SHGC: 0.49
Visual transmittance: 0.69
EN19,
Controls
Occupancy and daylighting sensors
EL6, DL17
Fixture Design
15% direct/85% indirect T5 pendent fixtures
EL3
Equipment
Fan-powered VAV w/displacement ventilation
HV5–6
Boilers
94% efficiency HW condensing
HV26
Cooling
Air-cooled chiller (10.7 EER)
HV25
Pumping
Variable-frequency drives (VFDs) on hot-water and chilled-water loops. HV25–26
Window Design
Operable for natural ventilation
HV32
Energy Recovery
Desiccant well
HV9
SWH
94% efficient condensing (gas)
WH1–2
Measurement and Verification
Systems Cx
HV23
Temperature Control
Web-based building automation system (BAS)
Demand-Controlled Ventilation
Gymnasium and cafeteria AHUs
Lighting
HVAC
System Controls
Additional Savings
Kitchen Equipment
Energy-efficient equipment (gas)
AS2
Energy Use Characteristics
Simulated Code Base
113.7 kBtu/ft2⋅yr
Simulated Design Model
53.7 kBtu/ft2⋅yr (original design—no summer operation)
Measured Energy Use
78.4 kBtu/ft2⋅yr (actual operation)
Years of Measured Data
3 years
Photos and data are provided by Elk River Area School District ISD 728 and Johnson Controls.
Chapter 4—Case Studies | 73 Zone 6—Alder Creek Middle School
Truckee, California
Alder Creek Middle School near Lake Tahoe is located in a rural setting in climate
zone 6. The 87,000 ft2 building opened in 2004. The school was designed to serve 1000
students with an initial capacity of 700 students in sixth through eighth grades. The project
was a CHPS demonstration school with a construction cost of $24 million ($30 million
with contingency and soft costs), or $275/ft2.
The school is a showcase of high-performance building strategies, including daylighting, energy efficiency, healthy IAQ, proper acoustics, building Cx, sustainable materials,
waste reduction, preventive maintenance, site protection, and water conservation. The
spaces in the school include classrooms, offices, public assembly spaces, cafeteria, gymnasium, athletic fields, and restrooms.
Classroom light fixtures are 60% uplight and 40% downlight. The top row of windows
is designed to provide daylight to the space. Ground-source heat pumps (GSHPs) operate
with an energy savings of more than 51% compared to the typical four-pipe boiler chiller
system previously installed. The school uses 288 wells that are drilled 300 ft deep beneath
the soccer field.
UPPER FLOOR
LEGEND
AD Administration
AU Auditorium
CC Covered Circulation
CR Classroom
E Electrical
EC Enclosed Circulation
G Gymnasium
J Janitorial
KT Kitchen
L Lab/Learning Center
M Mechanical
MP Multipurpose Room
P Portable Classroom
PO Pull-Out Classroom
S Storage
T Toilets
W Work Room
Location of well field
(288 wells approx. 315’ deep)
ALDER CREEK MIDDLE SCHOOL
Figure 4.19. Site plan showing geothermal well field location
74 | Advanced Energy Design Guide for K-12 School Buildings
(b)
(a)
Figure 4.20. Alder Creek Middle School (a) classroom lighting system and (b) daylighted gym.
Table 4.9. Alder Creek Middle School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
Long east-west axis
DL9
Opaque Components
Roof and walls R-19; cool roof
EN1, EN3, EN7
Vertical Glazing
Low-e
EN19
Lighting Systems Used
T5 direct/indirect in classrooms and offices;
T5 HO in gym;
T8 in all other areas
EL2–3
Controls
Sensor on row of lights near windows;
Room occupancy sensors
EL6
Window Design
Low-e with dual glazing
DL1–4
Controls
Blinds inside windows act as light shelves
DL12
Skylights
Located in stairwells in classroom wing
Lighting
Daylighting
HVAC
Equipment
GSHPs
HV2
Boilers
Backup and peak use only
HV26
SWH
Dedicated domestic boiler for hot water
WH1–2
Measurement and Verification
EMCS system used district wide
HV23
Temperature Control
Individual room controls with a 5° limit on user control
CO2 Sensors
Used in gym and cafeteria
System Controls
Additional Savings
Computers
Energy Star features enabled
AS2
Exterior/Field/Parking Lot Lighting
Metal halide lamps
EX1–3
Energy Use Characteristics
Simulated Energy Use
25% below Title 24 in California
Measured Energy Use
54 kBtu/ft2⋅yr
Years of Measured Data
2.75 years
Photos and data are provided by the Tahoe Truckee Unified School District, CHPS case study, and Lionakis Beaumont Design Group, Inc.
Chapter 4—Case Studies | 75 Zone 7—Silverthorne Elementary School
Silverthorne, Colorado
Silverthorne Elementary in Silverthorne, Colorado, is located in Summit County in
climate zone 7. Silverthorne is a 62,500 ft2 building that houses 430 students ranging from
K-5. The school opened in the fall of 2004. The build cost of the school was $9.3 million,
or $148/ft2, which is in line with the typical cost of area schools. The building was designed
by OZ Architecture of Denver in collaboration with BOORA of Portland Oregon.
At an elevation of 9100 ft, the extreme climate was a factor in the design. By optimizing the building orientation, using daylighting to the fullest, increasing insulation levels,
and using natural ventilation and economizers, the design team developed a design that will
save the district $27,000 per year that would otherwise be spent on high utility bills. On
warm days, outdoor air enters through the windows and rises to the top floor atria where
it is vented by exhaust fans. When windows are closed, efficient mechanical ventilation is
used. VAV air handlers deliver fresh air to the rooms and are regulated by CO2 sensors to
ensure adequate ventilation. This design also keeps air-handler noise away from the classrooms, improving acoustics in learning areas.
The design team’s goal was for daylighting to provide most of the light needed in
classrooms, even on overcast days. In addition to ample windows, daylight is directed to
illuminate the back wall of each classroom using light shafts. Daylighting controls in the
classrooms and gyms control lights in response to the available daylighting.
Figure 4.21. Interior view of skylights.
76 | Advanced Energy Design Guide for K-12 School Buildings
(a)
(b)
Figure 4.22. (a) Silverthorne Elementary School exterior and (b) classroom lighting system.
Table 4.10. Silverthorne Elementary School
Energy Saving Measures
Description
Tips
Envelope
Building Orientation
Long east-west axis
DL9
Opaque Components
60 mil EPDM roof with R-30 polyiso insulation and
R-19 wall insulation
EN1, EN7
Vertical Glazing
Clear double pane with spectrally selective low-e coating EN19
Lighting
T-5 linear indirect classrooms and offices;
high bay metal halide in gym
EL3, EL5
Controls
Occupancy sensors in all rooms and offices
EL6
Daylighting Controls
Automatic dimming and separate controls for each
row of lights in classrooms
EL8
Window Design
Aluminum frame windows that are thermally broken
DL1–4
Daylighting Design
Light shelves on exterior southern exposure;
clerestories for interior hallways; light shafts in back of
every classroom; skylight spines along central
circulation path, gym and admin offices (see photos)
DL12
Equipment
AHUs have VAV with reheat;
cooling is by outdoor air economizer cycle
HV6
Boilers
Condensing boilers with 90+% efficiency
HV26
Cooling Tower
None
Economizer
Economizer cycle for all cooling
HV13
Service Water Heating
Solar preheat for domestic hot water
WH1, WH3, WH5–6, AS7
System Controls
HVAC controls include limiting outdoor air during
unoccupied hours, optimum start/stop and outdoor
air reset on heating hot water.
HV21
Cx
Partial commissioning
HV23
OA Control
Individual rooms with CO2 sensors
Daylighting
HVAC
Additional Savings
Computers
Energy Star
AS2
Renewable Energy
Solar preheat for hot water
AS7
Energy Use Characteristics
Simulated Energy Use
76.7 kBtu/ft2⋅yr
Measured Energy Use
88.0 kBtu/ft2⋅yr
Years of Measured Data
2 years